Spring Equinox: Greet the date that gives you an equal amount of day and night

Tradition meets science as Holi falls a day after equinox — both heralding the end of winter.

 |  3-minute read |   20-03-2019
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It is spring, it is Holi and it is the equinox. 

Today marks this year’s spring equinox — the day when the sun is directly above the equator.

This makes the day and night the same length of time. Extending the logic, the northern and the southern hemispheres would be equally illuminated.  

The equinox occurs twice each year — on March 20/21 and September 22/23. Both these days witness equal day and night timings — both the days when the sun is directly above the equator.

In the northern hemisphere, the March equinox — since it marks the end of winter and ushers in a warmer climate — is called Vernal or Spring Equinox. On the other hand, the September equinox — marking the end of summer and ushering in the autumn and a colder climate — is called the Autumnal or Fall Equinox. The southern hemisphere would see an exactly opposite pattern.

The word “equinox” traces its roots to the Latin word 'aequinoctium', derived from 'aequus' — meaning 'equal', and and the word 'nox' from genitive root 'noctis' — meaning 'night'.

main_equinox-1_032019030450.jpgPeople raise their arms towards the sun to welcome the spring equinox in front of the Pyramid of the Sun in Teotihuacan, near Mexico City. (Photo: Reuters)

It is said that when Julius Caesar established the Julian calendar in 45 BC, he set March 25 as the date of the spring equinox — a day that already marked the beginning of the New Year in the Persian and Indian calendars.

The Iranian New Year — called Nowruz — is celebrated on the equinox. The same is followed by the Zoroastrians, whose new year coincides with the Iranian. The Iranian tradition was passed onto Central Asians — Kazakhs, Uzbeks, Uighurs — who celebrate the new year on this day called Nauryz.

Closer home, remember Ugadi, Bihu, Puttandu, Vishu, Noboborsho and other new years celebrated in India? All of these are celebrated around or within a fortnight of the equinox.

In ancient cultures, when people did not have clocks to calculate minutes of daytime and nighttime, they would measure the sun’s position geometrically.

The astronomers back then observed that the sun’s rising and setting points moved slightly each day of the year — the two days of the year when the sun rose exactly due east and set exactly due west marked the equinoxes.

However, with the advent of more precise and advanced time measuring instruments and technology, scientists found that the day and night time length varies according to the observer’s geographical location and the sunrise — and the sunset tables defined that the day is about seven to 14 minutes longer (depending on your location) than the night time in the northern hemisphere.

Sorry to burst the bubble, folks!

Nonetheless, it heralds a happier, warmer climate and harvest season globally.

Happy spring, happy equinox and a very happy Holi!

Also read: Super snow moon: Tonight, the lunar orb will present a rare visual treat for earth dwellers

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